scholarly journals Lack of Indinavir Effects on Methadone Disposition Despite Inhibition of Hepatic and Intestinal Cytochrome P4503A (CYP3A)

2012 ◽  
Vol 116 (2) ◽  
pp. 432-447 ◽  
Author(s):  
Evan D. Kharasch ◽  
Pamela Sheffels Bedynek ◽  
Christine Hoffer ◽  
Alysa Walker ◽  
Dale Whittington
Keyword(s):  
Plasma Concentration ◽  
Drug Interactions ◽  
Plasma Concentrations ◽  
Antiretroviral Drugs ◽  
Cyp3a Activity ◽  
Oral Clearance ◽  
Hepatic Extraction ◽  
Time Curve ◽  
Apparent Oral Clearance ◽  
First Pass

Background Methadone disposition and pharmacodynamics are highly susceptible to interactions with antiretroviral drugs. Methadone clearance and drug interactions have been attributed to cytochrome P4503A4 (CYP3A4), but actual mechanisms are unknown. Drug interactions can be clinically and mechanistically informative. This investigation assessed effects of the protease inhibitor indinavir on methadone pharmacokinetics and pharmacodynamics, hepatic and intestinal CYP3A4/5 activity (using alfentanil), and intestinal transporter activity (using fexofenadine). Methods Twelve healthy volunteers underwent a sequential crossover. On three consecutive days they received oral alfentanil plus fexofenadine, intravenous alfentanil, and intravenous plus oral (deuterium-labeled) methadone. This was repeated after 2 weeks of indinavir. Plasma and urine analytes were measured by mass spectrometry. Opioid effects were measured by miosis. Results Indinavir significantly inhibited hepatic and first-pass CYP3A activity. Intravenous alfentanil systemic clearance and hepatic extraction were reduced to 40-50% of control, apparent oral clearance to 30% of control, and intestinal extraction decreased by half, indicating 50% and 70% inhibition of hepatic and first-pass CYP3A activity. Indinavir increased fexofenadine area under the plasma concentration-time curve 3-fold, suggesting significant P-glycoprotein inhibition. Indinavir had no significant effects on methadone plasma concentrations, methadone N-demethylation, systemic or apparent oral clearance, renal clearance, hepatic extraction or clearance, or bioavailability. Methadone plasma concentration-effect relationships were unaffected by indinavir. Conclusions Despite significant inhibition of hepatic and intestinal CYP3A activity, indinavir had no effect on methadone N-demethylation and clearance, suggesting little or no role for CYP3A in clinical disposition of single-dose methadone. Inhibition of gastrointestinal transporter activity had no influence of methadone bioavailability.

scholarly journals Methadone Pharmacokinetics Are Independent of Cytochrome P4503A (CYP3A) Activity and Gastrointestinal Drug Transport

2009 ◽  
Vol 110 (3) ◽  
pp. 660-672 ◽  
Author(s):  
Evan D. Kharasch ◽  
Christine Hoffer ◽  
Dale Whittington ◽  
Alysa Walker ◽  
Pamela Sheffels Bedynek
Keyword(s):  
Steady State ◽  
Plasma Concentration ◽  
Drug Interactions ◽  
Drug Transport ◽  
Plasma Concentrations ◽  
Cyp3a Activity ◽  
Oral Clearance ◽  
Healthy Human ◽  
Apparent Oral Clearance ◽  
P Glycoprotein

Background Methadone clearance is highly variable, and drug interactions are problematic. Both have been attributed to CYP3A, but actual mechanisms are unknown. Drug interactions can provide such mechanistic information. Ritonavir/indinavir, one of the earliest protease inhibitor combinations, may inhibit CYP3A. We assessed ritonavir/indinavir effects on methadone pharmacokinetics and pharmacodynamics, intestinal and hepatic CYP3A activity, and intestinal transporters (P-glycoprotein) activity. CYP3A and transporters were assessed with alfentanil and fexofenadine, respectively. Methods Twelve healthy human immunodeficiency virus-negative volunteers underwent a sequential three-part crossover. On three consecutive days, they received oral alfentanil/fexofenadine, intravenous alfentanil, and intravenous plus oral (deuterium-labeled) methadone, repeated after acute (3 days) and steady-state (2 weeks) ritonavir/indinavir. Plasma and urine analytes were measured by mass spectrometry. Opioid effects were assessed by miosis. Results Alfentanil apparent oral clearance was inhibited more than 97% by both acute and steady-state ritonavir/indinavir, and systemic clearance was inhibited more than 90% due to diminished hepatic and intestinal extraction. Ritonavir/indinavir increased fexofenadine area under the plasma concentration-time curve four- to five-fold, suggesting significant inhibition of gastrointestinal P-glycoprotein. Ritonavir/indinavir slightly increased methadone N-demethylation, but it had no significant effects on methadone plasma concentrations or on systemic or apparent oral clearance, renal clearance, hepatic extraction or clearance, or bioavailability. Ritonavir/indinavir had no significant effects on methadone plasma concentration-effect relationships. Conclusions Inhibition of both hepatic and intestinal CYP3A activity is responsible for ritonavir/indinavir drug interactions. Methadone disposition was unchanged, despite profound inhibition of CYP3A activity, suggesting little or no role for CYP3A in clinical methadone metabolism and clearance. Methadone bioavailability was unchanged, despite inhibition of gastrointestinal P-glycoprotein activity, suggesting that this transporter does not limit methadone intestinal absorption.

scholarly journals Fosamprenavir with Ritonavir Pharmacokinetics during Pregnancy

2020 ◽  
Vol 64 (4) ◽  
Author(s):  
Ahizechukwu C. Eke ◽  
Jiajia Wang ◽  
Khadija Amin ◽  
David E. Shapiro ◽  
Alice Stek ◽  
...  
Keyword(s):  
High Performance ◽  
Geometric Mean ◽  
Plasma Concentrations ◽  
Area Under The Curve ◽  
Oral Clearance ◽  
Time Curve ◽  
Apparent Oral Clearance ◽  
Pregnancy And Postpartum ◽  
Trough Concentrations ◽  
Median Area

ABSTRACT The purpose of this study was to evaluate the pharmacokinetics of ritonavir-boosted fosamprenavir during pregnancy and postpartum. Amprenavir (the active moiety of fosamprenavir) and ritonavir intensive pharmacokinetic evaluations were performed at steady state during the second and third trimesters of pregnancy and postpartum. Plasma concentrations of amprenavir and ritonavir were measured using high-performance liquid chromatography. The target amprenavir area under the concentration-versus-time curve (AUC) was higher than the 10th percentile (27.7 μg · h/ml) of the median area under the curve for ritonavir-boosted fosamprenavir in adults receiving twice-daily fosamprenavir-ritonavir at 700 mg/100 mg. Twenty-nine women were included in the analysis. The amprenavir AUC from time zero to 12 h (AUC0–12) was lower (geometric mean ratio [GMR], 0.60 [confidence interval {CI}, 0.49 to 0.72] [P < 0.001]) while its apparent oral clearance was higher (GMR, 1.68 [CI, 1.38 to 2.03] [P < 0.001]) in the third trimester than postpartum. Similarly, the ritonavir AUC0–12 was lower in the second (GMR, 0.51 [CI, 0.28 to 0.91] [P = 0.09]) and third (GMR, 0.72 [CI, 0.55 to 0.95] [P = 0.005]) trimesters than postpartum, while its apparent oral clearance was higher in the second (GMR, 1.98 [CI, 1.10 to 3.56] [P = 0.06]) and third (GMR, 1.38 [CI, 1.05 to 1.82] [P = 0.009]) trimesters than postpartum. The amprenavir area under the curve exceeded the target for 6/8 (75%) women in the 2nd trimester, 18/28 (64%) in the 3rd trimester, and 19/22 (86.4%) postpartum, and the trough concentrations (Cmin) of amprenavir were 4- to 16-fold above the mean amprenavir-protein-adjusted 50% inhibitory concentration (IC50) of 0.146 μg/ml. Although amprenavir plasma concentrations in women receiving ritonavir-boosted fosamprenavir were lower during pregnancy than postpartum, the reduced amprenavir concentrations were still above the exposures needed for viral suppression.

Design, Synthesis, and Pharmacokinetic Evaluation of O-Carbamoyl Tizoxanide Prodrugs

2020 ◽  
Vol 16 ◽  
Author(s):  
Xi He ◽  
Wenjun Hu ◽  
Fanhua Meng ◽  
Xingzhou Li
Keyword(s):  
Plasma Concentration ◽  
Broad Spectrum ◽  
Plasma Concentrations ◽  
Antiviral Drug ◽  
Systemic Exposure ◽  
Pharmacokinetic Profile ◽  
Hydroxyl Group ◽  
First Pass

Background: The broad-spectrum antiparasitic drug nitazoxanide (N) has been repositioned as a broad-spectrum antiviral drug. Nitazoxanide’s in vivo antiviral activities are mainly attributed to its metabolitetizoxanide, the deacetylation product of nitazoxanide. In reference to the pharmacokinetic profile of nitazoxanide, we proposed the hypotheses that the low plasma concentrations and the low system exposure of tizoxanide after dosing with nitazoxanide result from significant first pass effects in the liver. It was thought that this may be due to the unstable acyloxy bond of nitazoxanide. Objective: Tizoxanide prodrugs, with the more stable formamyl substituent attached to the hydroxyl group rather than the acetyl group of nitazoxanide, were designed with the thought that they might be more stable in plasma. It was anticipated that these prodrugs might be less affected by the first pass effect, which would improve plasma concentrations and system exposure of tizoxanide. Method: These O-carbamoyl tizoxanide prodrugs were synthesized and evaluated in a mouse model for pharmacokinetic (PK) properties and in an in vitro model for plasma stabilities. Results: The results indicated that the plasma concentration and the systemic exposure of tizoxanide (T) after oral administration of O-carbamoyl tizoxanide prodrugs were much greater than that produced by equimolar dosage of nitazoxanide. It was also found that the plasma concentration and the systemic exposure of tizoxanide glucuronide (TG) were much lower than that produced by nitazoxanide. Conclusion: Further analysis showed that the suitable plasma stability of O-carbamoyl tizoxanide prodrugs is the key factor in maximizing the plasma concentration and the systemic exposure of the active ingredient tizoxanide.

Exposure to Retinoic Acids in Non-Pregnant Women Following High Vitamin A Intake with a Liver Meal

2005 ◽  
Vol 75 (3) ◽  
pp. 187-194 ◽  
Author(s):  
Hartmann ◽  
Brørs ◽  
Bock ◽  
Blomhoff ◽  
Bausch ◽  
...  
Keyword(s):  
Plasma Concentration ◽  
Vitamin A ◽  
Safety Concern ◽  
Peak Plasma ◽  
Plasma Concentrations ◽  
Pregnant Female ◽  
Time Curve ◽  
High Vitamin ◽  
Concentration Time ◽  
Plasma Concentration Time Curve

Animal liver is a rich source of vitamin A. Due to retinoic acid (RA) metabolites, vitamin A has a teratogenic potential and women are generally advised to avoid or to limit the consumption of liver during pregnancy. In a recent study in non-pregnant female volunteers following single and repeated doses of up to 30,000 IU/day of vitamin A as a supplement, the plasma concentration time curve of all-trans RA acid showed a diurnal-like profile. But, the overall exposure (AUC24h) remained essentially unaltered whereas AUC24h increased linearly with dose for 13-cis and 13-cis-4-oxo RA. The current study in non-pregnant female volunteers showed that a single high vitamin A intake with a liver meal (up to 120,000 IU) exhibited a similar diurnal-like plasma concentration time curve for all-trans RA and its overall exposure remained also unaltered, despite a temporary two-fold increase in peak plasma concentration. Concentrations of 13-cis and 13-cis-4-oxo RA increased several-fold after a liver meal, and exposure (AUC24h) increased three- to five-fold. Pooling our results with data in the literature revealed a linear relation between the mean AUC24h of 13-cis and 13-cis-4-oxo RA and vitamin A intake with liver. Metabolism to all-trans RA of vitamin A with liver seems not to be of safety concern. However, the observed increase of plasma concentrations and the dose-dependent increase in exposure to 13-cis and 13-cis-4-oxo RA support the current safety recommendations on vitamin A intake and suggest that women should be cautious regarding their consumption of liver-containing meals during pregnancy.

Phase I/IIa, randomized, open-label, drug-drug interaction study of trabectedin and rifampin in patients with advanced cancer.

2013 ◽  
Vol 31 (15_suppl) ◽  
pp. e13512-e13512 ◽  
Author(s):  
Arthur P. Staddon ◽  
Trilok V. Parekh ◽  
Roland Elmar Knoblauch ◽  
Chi Keung ◽  
Apexa Bernard ◽  
...  
Keyword(s):  
Plasma Concentration ◽  
Locally Advanced ◽  
Plasma Concentrations ◽  
Systemic Exposure ◽  
Maximum Plasma ◽  
Metabolic Clearance ◽  
Open Label ◽  
Time Curve ◽  
Elimination Half ◽  
Cyp3a4 Inducer

e13512 Background: Trabectedin (Yondelis; T) is a tetrahydroisoquinoline compound initially isolated from the marine tunicate, Ecteinascidia turbinata, and currently produced synthetically. It is primarily metabolized by the cytochrome P450 (CYP)3A4 enzyme. Thus, potent inducers or inhibitors of this enzyme may alter the plasma concentrations of T. This study assessed the effects of rifampin (R), a strong CYP3A4 inducer, on the pharmacokinetics (PK) and safety of T. Methods: In this 2-way crossover study, patients (≥18 years of age) with locally advanced or metastatic disease were randomized (1:1) to receive one of the 2 treatment sequences: sequence 1: R plus T followed 28 days later by T; sequence 2: T followed 28 days later by R plus T. During each sequence, R (600 mg/day) was administered for 6 consecutive days and T (1.3 mg/m2, IV) was administered over a 3 hour infusion. Dexamethasone (20 mg, IV) was administered before T administration. PK and safety of T were evaluated with and without coadministration of R. Results: Of the 11 enrolled patients, 8 were PK evaluable. Coadministration of R with T decreased mean maximum plasma concentration (Cmax) by approximately 22% and mean area under the plasma concentration-time curve from time 0 to the last quantifiable concentration (AUClast) by approximately 31% (Table 1). Coadministration of R with T also resulted in 23% shorter elimination half-life. Overall, the safety profile of T was comparable when administered alone or with R. Conclusions: In comparison with T alone, coadministration of R resulted in reduced systemic exposure of T in these 8 patients, as measured by Cmax and AUClast. The coadministration of potent inducers of CYP3A4 with T may increase the metabolic clearance of T. Clinical trial information: NCT01273480. [Table: see text]

scholarly journals Risk Factors for a Low Linezolid Trough Plasma Concentration in Acute Infections

2013 ◽  
Vol 57 (4) ◽  
pp. 1913-1917 ◽  
Author(s):  
Laura Morata ◽  
Marta Cuesta ◽  
Jhon F. Rojas ◽  
Sebastian Rodriguez ◽  
Merce Brunet ◽  
...  
Keyword(s):  
Risk Factors ◽  
Steady State ◽  
Plasma Concentration ◽  
Plasma Concentrations ◽  
Time Curve ◽  
Content Type ◽  
Acute Infections ◽  
Trough Plasma Concentration ◽  
Dependent Activity ◽  
Trough Plasma

ABSTRACTLinezolid is an antibiotic with time-dependent activity, and both the percentage of time that plasma concentrations exceed the MIC and the area under the concentration-time curve over 24 h in the steady state divided by the MIC (AUC24/MIC ratio) are associated with clinical response. The aim of this study was to analyze the linezolid trough plasma concentration (Cmin) and to determine factors associated with aCmin< 2 mg/liter and other clinically relevant thresholds. Characteristics of 78 patients receiving 600 mg/12 h of linezolid with aCmindetermination at the steady state and within the first 10 days of treatment were retrospectively reviewed. Concentrations were measured using high-pressure liquid chromatography. Univariate and multivariate analysis were performed to identify risk factors of lowCmin. A total of 29.5% of patients had aCmin< 2 mg/liter. The percentage was significantly higher in patients with an estimated glomerular filtration (eGF) > 80 ml/min, in intensive care unit (ICU) patients, and in patients with an infection due toStaphylococcus aureus. The independent predictors ofCmin< 2 mg/liter were an eGF > 80 ml/min (odds ratio [OR], 10; 95% confidence interval [CI], 2.732 to 37.037;P= 0.001) and infection due toS. aureus(OR, 5.906; 95% CI, 1.651 to 21.126;P= 0.006). A linezolidCminof <2 mg/liter was found in 29.5% of cases, and the risk was significantly higher among those with an eGF > 80 ml/min and in infections due toS. aureus. In patients with severe sepsis, a loading dose or continuous infusion and drug monitoring could improve the pharmacodynamic parameters associated with linezolid efficacy.

Plasma Inorganic Fluoride Concentrations after Sevoflurane Anesthesia in Children

1996 ◽  
Vol 84 (2) ◽  
pp. 348-353. ◽  
Author(s):  
M. F. Levine ◽  
J. Sarner ◽  
J. Lerman ◽  
P. Davis ◽  
N. Sikich ◽  
...  
Keyword(s):  
Plasma Concentration ◽  
Elective Surgery ◽  
Plasma Concentrations ◽  
Sevoflurane Anesthesia ◽  
Inorganic Fluoride ◽  
Time Curve ◽  
Plasma Urea ◽  
The Mean ◽  
Group 2

Background Sevoflurane is degraded in vivo in adults yielding plasma concentrations of inorganic fluoride [F-] that, in some patients, approach or exceed the 50- micron theoretical threshold for nephrotoxicity. To determine whether the plasma concentration of inorganic fluoride [F-] after 1-5 MAC x h sevoflurane approaches a similar concentration in children, the following study in 120 children scheduled for elective surgery was undertaken. Methods Children were randomly assigned to one of three treatment groups before induction of anesthesia: group 1 received sevoflurane in air/oxygen 30% (n = 40), group 2 received sevoflurane in 70% N2O/30% O2 (n = 40), and group 3 received halothane in 70% N2O/30% O2 (n = 40). Mapleson D or F circuits with fresh gas flows between 3 and 61/min were used Whole blood was collected at induction and termination of anesthesia and at 1, 4, 6, 12, and 18 or 24 h postoperatively for determination of the [F-]. Plasma urea and creatinine concentrations were determined at induction of anesthesia and 18 or 24 h postoperatively. Results The mean (+/- SD) duration of sevoflurane anesthesia, 2.7 +/- 1.6 MAC x h (range 1.1-8.9 MAC x h), was similar to that of halothane, 2.5 +/- 1.1 MAC x h. The peak [F-] after sevoflurane was recorded at 1 h after termination of the anesthetic in all but three children (whose peak values were recorded between 4 and 6 h postanesthesia). The mean peak [F-] after sevoflurane was 15.8 +/- 4.6 microns. The [F-] decreased to &lt;6.2 microns b 24 h postanesthesia. Both the peak [F-] (r2 = 0.50) and the area under the plasma concentration of inorganic fluoride-time curve (r2 = 0.57) increased in parallel with the MAC x h of sevoflurane. The peak [F-] after halothane, 2.0 +/- 1.2 microns, was significantly less than that after sevoflurane (P&lt;0.00012) and did not correlate with the duration of halothane anesthesia (MAC x h; r2 = 0.007). Plasma urea concentrations decreased 24 h after surgery compared with preoperative values for both anesthetics (P&lt;0.01), whereas plasma creatinine concentrations did not change significantly with either anesthetic. Conclusions It was concluded that, during the 24 h after 2.7 +/- 1.6 MAC x h sevoflurane, the peak recorded [F-] is low (15.8 microns), F- is eliminated rapidly, and children are unlikely to be at risk of nephrotoxicity from high [F-].

Interaction of Metoprolol, Propranolol and Atenolol with Cimetidine

1982 ◽  
Vol 63 (s8) ◽  
pp. 451s-453s ◽  
Author(s):  
W. Kirch ◽  
H. Spahn ◽  
H. Köhler ◽  
E. Mutschler
Keyword(s):  
Plasma Concentration ◽  
Healthy Volunteers ◽  
Peak Plasma ◽  
Plasma Concentrations ◽  
Concurrent Administration ◽  
Time Curve ◽  
Concentration Time ◽  
Plasma Concentration Time Curve

1. Pharmacokinetics of metoprolol, propranolol and atenolol were investigated in six healthy volunteers after 7 days of oral monotherapy with these drugs and after 7 days concurrent administration, with each of these β-adrenoceptor antagonists with cimetidine. 2. Cimetidine did not interact with atenolol, whereas mean peak plasma concentrations of metoprolol were increased by 70%, and those of propranolol by 95% with concurrent administration of cimetidine (P < 0.05). 3. The area under the plasma concentration-time curve for propranolol and metoprolol was similarly increased (P < 0.05).

scholarly journals Pharmacokinetic herb-drug interactions between Aidi injection and Doxorubicin in rats with diethylnitrosamine-induced hepatocellular carcinoma

2020 ◽  
Author(s):  
Yuan Lu ◽  
Jie Pan ◽  
Xiaoqing Zhu ◽  
Shuai Zhang ◽  
Liu Chunhua ◽  
...  
Keyword(s):  
Hepatocellular Carcinoma ◽  
Drug Interactions ◽  
Plasma Concentrations ◽  
Ultra Performance Liquid Chromatography ◽  
Limited Information ◽  
Time Curve ◽  
Anti Cancer ◽  
Liquid Chromatography Tandem Mass ◽  
Aidi Injection ◽  
Reduced Toxicity

Abstract Background: Aidi Injection (ADI), a Chinese herbal preparation with anti-cancer activity, is used for the treatment of hepatocellular carcinoma (HCC). Several clinical studies have shown that co-administration of ADI with doxorubicin (DOX) is associated with reduced toxicity of chemotherapy, enhanced clinical efficacy and improved quality of life for patients. However, limited information is available about the herb-drug interactions between ADI and DOX. The study aimed to investigate the pharmacokinetic mechanism of herb-drug interactions between ADI and DOX in a rat model of HCC. Methods: Experimental HCC was induced in rats by oral administration of diethylnitrosamine. The HCC rats were pretreated with ADI (10 mL/kg, intraperitoneal injection) for 14 consecutive days prior to administration of DOX (7 mg/kg, intravenous injection) to investigate pharmacokinetic interactions. Plasma concentrations of DOX and its major metabolite, doxorubicinol (DOXol), were determined using ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Results: Preadministration of ADI significantly altered the pharmacokinetics of DOX in HCC rats, leading to increased plasma concentrations of both DOX and DOXol. The area under the plasma drug concentration-time curve (AUCs) of DOX and DOXol in rats pretreated with ADI were 3.79-fold and 2.92-fold higher, respectively, than those in control rats that did not receive ADI. Conclusions: Increased levels of DOX and DOXol were found in the plasma of HCC rats pretreated with ADI.

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